sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

We first spotted these guys a couple years back when they were showing off the first prototypes, which had a hardwired connection at the base of the Sinewave Reactor  USB charger top cap. Now, they’re in full production and have made a few mods to make them more user friendly.

The Reactor is a sealed USB port that connects to a dynamo hub to charge anything that’ll pull power through a USB cable, and it’s conveniently located on the bike’s steerer tube. The main change is a snap connector at the base that allows the top cap to be removed without having to pull wires all the way up from the hub…

sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

Two ports on the bottom are tight enough to hold the wires in place, but not overly snug such that they tug at the electronics inside when the cables are removed.

sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

With a little excess coil bundled up between the expansion wedge and the Reactor, the cables aren’t going to fall out.

sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

The other benefit of having a plug ‘n’ play system is that you can split the cable at the top to fit between the star wedge rather than having to split it all the way from the bottom.

sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

Three colors are available.

sinewave cycles reactor usb charger headset cap for bicycle dynamo hubs

They also make the Revolution charger, which offers the same electronics but can be placed inside a pannier/handlebar bag or strapped elsewhere on the frame. Retail is $220 for the Reactor and $120 for the Revolution.


  1. Not in the market for a dynamo hub myself… but wondering why no one has produced a USB steertube battery already? It would be perfect for some of those battery-pack powered front lights, or to keep your smartphone charged (if you choose to mount it in the cockpit). The battery portion could be swapped out and recharged say 1x a week or whatever interval suits your usage.

  2. Dynamo hubs seem to me to be the future if we can work out some issues. We could save battery weight by half if our hubs provided a constant recharge. Problem is they provide resistance that slows us down. Sounds “Enduro”…lol

  3. @Ripnshread The resistance in a dynamo is required to produce power – no resistance means no power. The best ones are already around 75% efficient (you spend 4W muscle power to get 3W electrical power), so there’s not much more left to gain. Few are able to feel those 4 watts anyway, it just means you get a tiny bit more exercise. Dynamos are not just the future but the past and present also! 🙂

  4. @ Ripnshread

    Yes, they do provide some resistance, but less than you might think. It really depends on how much current you’re drawing from them. In the case of a modern LED light set, most people can’t tell the difference.

  5. I think people in the US are starting to get a clue about dynamo hubs. Yesterday the next bike in the rack at work was a shiny new titanium road bike with disc brakes and dynamo lights. LED lights and continuing mechanical development make dyno lights better than ever and being able to juice up your smart phone is probably a selling point for some folks.

  6. …or the GPS. I do occasionally empty the Edge 800, and I hear the 1000 has much less battery life. Being able to just keep going as far as I’m able to turn the cranks, with backlight on if necessary, is great when touring.

  7. @Durianrider The velogical is very light weight, efficient, easily fitted, and can be turned off. Downside, it’s expensive and it sounds like you have an electric motor. A dynohub is (can be) cheaper, also efficient, offers a cleaner installation, and is perfectly silent, thought it (most) can’t be turned off, is heavy, and if you want to switch wheel sets you need two. I should know, I use both kinds, on different bikes. Both are good.

  8. For everyone excited about recharging their computer/GPS on the go, I’ve tried my “The Plug III” with a Garmin Edge 810 and Edge 1000 for multi-day touring and randonneuring. Both of the computers have hardware limitations such that they continuously go out of operating mode and into a recharging mode when you plug them into the USB outlet once the dynamo starts generating an output.

    In other words: we seem to have the same great idea that Garmin’s engineers haven’t.

  9. @Seth Agreed, the Luxos U is great. I’d only recommend another charging solution if you already have good quality dynamo light you want to keep.

    @Matthew That sucks. It doesn’t happen with my “old” Edge 800. Weird that Garmin should get it right at first, and then screw it up. (The 800 isn’t perfect either. Whenever dyno power kicks in, the screen goes to maximum brightness – not nice at night. But it does charge, while staying in normal operating mode.)

  10. Matthew, change your connector cable from the data USB to a charge-only USB and it’ll work fine. Mine does. Add a small storage rc battery to the system and you don’t even get the ‘charge lost’ screen at low speeds.

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